“I believe that very quickly Detroit’s going to become known as one of the most important start-up cities in the United States,” Linkner told Detroit 2020.

Within the walls of the Madison Building, you’re beginning to see that come to life, with companies such as Quikly, Doodle Home, and Detroit Labs.

“They are building mobile apps for some of the biggest brands and companies in the world. It’s a company we launched only a year ago. They’re already profitable. They have millions of dollars in revenue, 30 some employees and it’s all happening right here in the ‘D’, Linkner said.

And it’s all happening in a cool workspace.

The Madison Theatre is gone, but the building was preserved after decades of decay. Cement floors, exposed brick, and steel beams give it an urban feel. Some of the graffiti, courtesy of urban explorers, also remains.

“This is a city with a soul and to have that grit and determination that allowed our city to prosper in the first place–and re-applying it in the tech world today–I can’t think of anything more exciting,” Linkner said.

The Madison is one of 15 downtown buildings businessman Dan Gilbert has purchased since January of 2011. Gilbert is also a general partner in the venture capital firm. They’re driven to make a difference.

“The nice thing about an entrepreneur building their company here rather than someplace else, is you can actually leave your fingerprints, you now. If I built a company in Silicon Valley, nobody would care. Here in Detroit, it matters. Everything you do matters,” Linkner said.

A driving force for change. That’s the goal.

Here’s a list of companies located in the Madison Building:

Twitter: A real-time information network that connects people to the latest stories, ideas, opinions and news

Whip Hand Cosmetics: Cosmetic company that celebrates today’s modern women while being manufactured in Detroit, Michigan

Brys & Edgewood: A company that produces DIY fondant kits and cupcake kits that are easy enough for anyone to make at home

Chalkfly: An office and school supply company that is rooted in giving back to teachers across the nation while providing customers with quality office supplies, innovative technology, and exceptional service